In many television systems a particular characteristic of a video signal is detected in order to generate a control signal. For example, concurrently filed U.S. patent application Ser, No. 398,845 filed Aug. 25, 1989, entitled "A DYNAMIC VIDEO SYSTEM INCLUDING AUTOMATIC CONTRAST AND `WHITE-STRETCH` PROCESSING SECTIONS", referred to above, discloses a system for detecting the average value of a signal representing luminance information in order to generate a control signal for controlling the non-linear gain characteristic of a "white-stretch" processing section to enhance the contrast of a reproduced image. In other video control systems, it may be necessary to detect other characteristics of a luminance-representative signal, e.g., such as its peak-to-peak value. At any rate, it is desirable to utilize a luminance-representative signal which reflects contrast and/or brightness adjustments affecting the image content. Unfortunately, such a luminance-representative signal may not be readily available for detection when an integrated circuit incorporating luminance and chrominance signal processing sections is utilized. The present invention is directed to that dilemma.